Automatic cut-out safety device for hydraulic systems



Jan. 16, 1934. I R. c. LAMOND 1,943,535

AUTOMATIC CUT-OUT SAFETY DEVICE FOR HYDRAULIC SYSTEMS I Filed March 31,1931 2 Sheets-Sheet 1 Jan. 16, 1934. I R LAMOND 1,943,535

AUTOMATIC CUT-OUT SAFETY DEVICE FOR HYDRAULIC SYSTEMS Filed March 31,1931 2 Sheets-Sheet 2 Patented Jan. 16, 1934 UNITED STATES PATENT OFFICEAUTOMATIC CUT-OUT SAFETY DEVICE FOR U HYDRAULIC SYSTEMS ApplicationMarch 31,1931. Serial No. 526,749

6 Claims.

This invention relates to improvements in hydraulic apparatus, and moreparticularly in reciprocating fluid motors of the plunger type adaptablefor use in steering mechanisms.

An object of the invention is to provide a motor of the stated typecomprising novel means for limiting the travel of the plungers in theirworking strokes, thereby to prevent undesirable overtravel of theplungers and development of exl cessive pressures in the cylinders.

In its specific application to steering machines, an object of theinvention is to provide novel means actuated by over-travel of theoperating parts for bypassing the pressure in the working 1 cylinders ofthe motor to prevent damage to any part of the apparatus.

More particularly, the invention has for an object the provision of aplunger and cylinder assembly, constituting a reversible fluid motor,comprising means operative by a predetermined travel of the plungers inthe cylinders for bypassing the actuating fiuid from thecylinders underpressure to those under suction, as hereinafter more fully set forth.

The invention further resides in certain mechanical details hereinafterdescribed and illustrated in the attached drawings, in which:

Figure 1 is a plan view of a fluid motor having control means made inaccordance with my invention;

Fig. 2 is an end elevation of the motor;

Fig. 3 is a vertical sectional view illustrating the details of thebypass valve;

Fig. 4 is a horizontal sectional view illustrating details of thecontrol valve, and

Fig. 5 is areduced diagrammatic plan view illustrating application ofthe motor to a steering gear. I

- With reference to the drawings, a fluid motor -made in accordancewithmy invention may cornprise a pair of plungers 1 and 2, the opposite endsof each of which are disposed in working cylinders numbered,respectively, 3, 4, 5 and 6. To the outer end of each of the cylindersis connected to pipe 7 through which fluid under pressure may beintroduced to the said cylinders to actuate the plungers, or may bewithdrawn therefrom as the direction of movement of the plungers mayrequire. In a typical installation employing a motor of this character,the plungers 1 and 2 are adapted to move simultaneously in oppositedirections, and suitable pumping apparatus forming no part of thepresent invention is provided to supply fluid pressure simultaneously tothe two diagonally disposed cylinders 3-6 or 45, while the other pair ofdiagonally disposed cylinders are exhausted, whereby the desiredopposite movements of the plungers 1 and 2 are accomplished.

In accordance with my present invention, I provide at each end of theassembly a bypass duct, 8 and 9 respectively, each bypass containing avalve ll, see Fig. 3, and a check valve 12. The valve 11, see Fig. 3,consists of a housing 13 containing a valve 14 of the poppet type, which5 when seated, as illustrated, breaks communication between the oppositeends 01' the bypass ducts which connect respectively with the adja- Icent cylinders. A spring 15 is employed tending normally to hold thevalve to its seat and funco tioning to insure a prompt re-seating of thevalve 1 following elevation, as hereinafter set forth. The valve 14 hasa stem 16 which carries at its lower end a piston 17 operating in acylinder 18, the piston 17 having a greater effective pressure area 75than the valve 14 for a purpose hereinafter set forth. The lower end ofthe cylinder 18 of the valve 11 associated with the duct 8 is connectedthrough a pipe 19 with athree-way valve 21, this valve being alsoconnected through a pipe 22 50 with the outer end of the cylinder 4. Thevalve 21, as shown in Fig. 4, has three ports, two of which are incommunication with the pipes 19 and 22, while from the third port a pipe23 extends to a suitable reservoir or leakage tank as- 35 sociatedpreferably with the fluid supply for the motor-actuating pumps (notshown). The valve 21 is of such character that in alternative positionsit connects the pipe 19 with the pipe 22 and the pipe 23 respectively.Referring to Fig. 4, in which the valve is shown connecting the pipes 19and 23, it will benoted that a 90 oscillation of the valve proper willresult in a connection of the pipes 19 and 22 to the exclusion of thepipe 23.-

The cylinder 18 of the valve 11 of the bypass duct 9 is similarlyconnected through a pipe 24 with a three-way valve 25, this valve beingidentical with the valve 21 described above and comprising three ports,one of which communicates with the pipe 24, a second through a pipe 26with 0 the outer end of the cylinder 3 and the third port connectsthrough a suitable pipe with the afore-' said leakage tank. The valve 25in alternative positions connects the pipe 24 with the pipe 26 and thepipe 24 with the said leakage tank to the exclusion ofthe pipe 26.

The plunger 2: is provided with a pair of projecting fingers 27 and 28,the finger 27 being adapted to ,engage projections 29 and 30 on the stemof the valve 21, see broken line position,

while the finger 28 is adapted to engage similar projections 31 and 32on the stem of the valve 25. In the positions in which the valve isshown in Fig. 4, the said projections 29, 30, 31 and 32 are located asillustrated in Fig. 1. As the plunger 2 approaches the end of its travelin either direction, one or other of the fingers 2'7 and 28 respectivelyengages the projection 29 or 31 and shifts the associated valve elementinto position in which either the pipe 19 is connected with the pipe 22,or the pipe 24 with the pipe 26. With the plungers moving in thedirections indicated by the arrows, the cylinders 4 and 5 necessarilyare receiving fluid pressure from the source, while the cylinders 3 and6 are being exhausted. Consequently, when the valve 21 is adjusted asdescribed above to connect the pipe 19 with the pipe 22, fluid pressurefrom the cylinder 4 is exerted under the piston 17 of the valve 11 ofthe bypass 8, this pressure corresponding to the pressure exerted on topof the valve element 14 through the bypass connection between the upperportion of the valve chamber and the cylinder 4. As previously setforth, the piston 17 is of greater diameter than the face of the valve14, and the pressure exerted through the pipe 24 is, therefore,suflicient to elevate the stem 16 and unseat the valve 14 against theopposing fluid pressure and the pressure of the spring 15. The

valve being opened, pressure is permitted to flow from the cylinder 4directly to the cylinder 6, and since the cylinder 4 is connected withthe cylinder 5, and the cylinder 6 with the cylinder 3, as previouslyset forth, a corresponding pressure equalization occurs in the cylinders3 and 5, actuation of the plungers being immediately suspended. v

Upon reversal of the fluid pressure from the pumping apparatus, thecylinders 3 and 6 receive the pressure, while the cylinders 4 and 5 areconnected with the suction. Equalization of the pressures in thecylinders through the bypass as previously described has resulted in animmediate return of the valve 14 to its seat through the action of thespring 15, and since bypassing of the pressure from the pressure to theexhaust cylinders is prevented by the check valves 12, the plungers areactuated in the reverse directions. The initial movement of the plunger2 in this direction eflects a re-adjustment of the valve 21 to itsoriginal position through the action of the finger 2'7 upon theprojection 30 whereby the cylinder 18 is again connected with theleakage tank. As the plunger 2 approaches the limit of its travel in thecylinder 5 and the plunger 1 in the cylinder 4, the finger 28 engagesthe finger 31 of the valve 25 which admits pressure to the valve 11 ofthe bypass 9 and opens the valve to permit bypassing of pressure fromthe cylinder 3 to the cylinder 5 with a consequent correspondingequalization of the pressures in the cylinders 4 and 6 and consequentimmediate cessation of the plunger operation. An initial movement of theplunger 2 towards the cylinder 6 results in a re-seating of the valve 25by engagement of the finger 28 with the projection 32 of the valve.

An application of the invention is illustrated in Fig. 5, wherein theplungers 1 and 2 are shown connected through rods 33 and 34 with theopposite ends of a yoke 35 attached to the rudder post 36 of a steeringgear. The pipes 7 of the cylinders 4 and 5 are jointly connected throughpipes 37 and 38 to one side of a reversible discharge pump 39; and thepipes 7 of the cylinders 3 and 6 are similarly connected through ipes 41and 42 to the other side of said pump. Pressure is thus applied to oneof these sets of cylinders simultaneously with an evacuation of theother set, and the pressure and evacuation may be reversed in the setsof cylinders by reversal of the pump discharge. The device describedabove positively precludes possibility of over-travel of the plungers 1and 2 or of the rudder sufiicient to bring them into contact with theends of the cylinders or with the hull of the vessel, and therebyprevents development of undue pressures which might result in damageeither to the motor parts or to the rudder assembly.

There may be modification without departure from the invention.

I claim:

1. An hydraulic motor comprising a pair of parallel rams, and cylindersembracing the opposite ends of each of said rams, of means forconnecting the diagonally opposite cylinders whereby pressure may beapplied to one of said connected pairs simultaneously with exhaustingthe other pair of cylinders, a bypass connecting the pairs of cylindersat the corresponding ends of the rams, valves controlling said bypasses,check valves permitting flow through said bypasses in one directiononly, and means associated with one or the rams for opening said bypassvalves individually and respectively as the ram approaches the limit ofits travel in the opposite directions whereby the fluid pressure in onediagonally connected pair of cylinders is automatically bypassed to thecylinders of the other pair.

2. An hydraulic motor comprising a pair of rams and cylinders embracingthe opposite ends of each of said rams, of means for connecting saidcylinders in pairs whereby pressure may be applied to one of saidconnected pairs simultaneously with evacuation of the other pair ofcylinders, bypasses connecting the cylinders of one pair individuallyand respectively with the cylinders of the other pair, valvescontrolling said bypasses, check valves permitting flow through saidbypasses in one direction only, and means associated with one of therams for opening the said bypass valves individually and respectively asthe ram approaches the limit of its travel in the opposite directionswhereby fluid pressure in the one pair of cylinders is automaticallybypassed to the cylinders of the other pair.

3. An hydraulic motor comprising a pair of rams and cylinders embracingthe opposite ends of each of said rams, of means for connecting saidcylinders in pairs whereby pressure may be applied to one of saidconnected pairs simultaneously with evacuation of the other pair ofcylinders, bypasses connecting the cylinders of one pair individuallyand respectively with the cylinders of the other pair, valvescontrolling said bypasses, pressure-operated means for opening saidbypass valves, means for connecting said pressure operated meansrespectively with one cylinder of each of said pairs, 2. pilot valvecontrolling each of said connections, and means associated with one ofthe rams for opening said pilot valves individually and respectively asthe ram approaches the limit of its travel in the opposite directionswhereby the fluid pressure in one of said connected pairs of cylindersis automatically bypassed to the cylinders of the other pair.

4. An hydraulic motor comprising a pair of rams and cylinders embracingthe opposite ends of each of said rams, of means for connecting saidcylinders in pairs whereby pressure may be applied to one of saidconnected pairs simultaneously with evacuation of the other pair ofcylinders, bypasses connecting the cylinders of one pair individuallyand respectively with the cylinders of the other pair, valvescontrolling said bypasses, pressure-operated means for opening saidbypass valves, means for connecting said pressure operated meansrespectively with one cylinder of each of said pairs, a pilot valvecon-' trolling each of said connections, means asso- 0 ciated with oneof the rams for opening said pilot valves individually and respectivelyas the ram approaches the limit of its travel in the opposite directionswhereby the fluid pressure in one of said connected pairs of cylindersis automatically bypassed to the cylinders of the other pair, and meansfor automatically re-closing said pilot valves following actuation tothe open position when the said ram is operated in the oppositedirections.

5. An hydraulic motor comprising a pair of mm, a working cylinder ateach end of each of said rams, the cylinders of one ram being connectedwith the cylinders of the other ram whereby pressure may be appliedsimultaneously to force the rams in opposite directions, bypassesconnecting the cylinders at the corresponding ends of the rainstogether, a valve for each of said bypasses, and means associated withone of said rams for individually opening said valves at predeterminedpoints in the travel of the ram in opposite directions respectively,said means comprising a pressure-operated device for opening each ofsaid valves, means connecting said devices respectively with thecylinders at opposite ends of one of said rams, a pilot valvecontrolling each of said connecting means, and means associated with theram of the other cylinders for actuating said pilot valves.

6. An hydraulic motor comprising, a pair of rams arranged substantiallyin side by side relation, cylinders embracing the opposite ends of eachof said rams, piping connecting the cylinders of one ram with thediagonally opposite cylinders of the other ram, whereby pressure may besimultaneously applied to either of said connected pairs of cylinderswhile exhausting the other, bypass means between said connected pairs ofcylinders, normally closed valves in said by pass means, one of saidvalves controlling the flow of fluid from the cylinders subjected topressure to the cylinders connected to exhaust when said rams areactuated in one direction, the other of said valves controlling the flowof fluid from the cylinders subjected to pressure to the cylindersconnected to exhaust when said rams are actuated in the reversedirection, means for opening one of said valves when the rams approach00 their limit of travel in one direction, means for opening the otherof said valves when the rams approach their limit of travel in thereverse direction, a pump for supplying fluid pressure to saidcylinders, and means for urging said valve to 105 closed position.

I ROBERT C. LAMOND.

